Department of Radiation Oncology, Toronto, ON, Canada.
ICES, Toronto, ON, Canada.
Breast Cancer Res Treat. 2019 Nov;178(1):221-230. doi: 10.1007/s10549-019-05377-8. Epub 2019 Jul 31.
A better understanding underlying radiation (RT) response after breast-conserving surgery (BCS) is needed to mitigate over-treatment of DCIS. The hazard ratio (HR) measures the effect of RT but assumes the effect is constant over time. We examined the hazard function adjusted for adherence to surveillance mammography to examine variations in LR risk and the effect of RT over time.
Crude hazard estimates for the development of LR in a population cohort of DCIS treated by BCS ± RT were computed. Multivariable extended Cox models and hazard plots were used to examine the association between receipt of RT and risk of each outcome adjusted for baseline covariates and adherence to mammography.
Population cohort includes 3262 women treated by BCS; 1635 received RT. Median follow-up was 13 years. LR developed in 364 women treated by BCS alone and 274 treated with RT. LR risk peaked at 2 years, declined until year 7, and then remained steady. The peak hazard of LR was associated with adverse features of DCIS. Early LR risk was attenuated in patients treated with RT but late annual risks of LR and invasive LR were similar among the two treatment groups. On multivariate analysis, RT was associated with a reduction in early LR risk (HR = 0.52, 95% CI 0.43-0.63, p < 0.0001) but did not reduce the risk of late LR (HR = 0.89, 95% CI: 0.67, 1.19, p = 0.44) (interaction, p = 0.002).
The effect of RT is not uniform over time and greatest in the first 7 years after BCS for DCIS, which can guide future research to understand mechanisms underlying RT response and optimize future management of DCIS.
为了减轻对 DCIS 过度治疗的程度，需要更好地了解保乳手术后（BCS）的放射治疗（RT）反应。风险比（HR）衡量 RT 的效果，但假设效果随时间保持不变。我们检查了调整了监测乳房 X 光检查依从性的危害函数，以检查 LR 风险的变化以及 RT 随时间的影响。
计算了接受 BCS ± RT 治疗的 DCIS 人群队列中发生 LR 的粗危害估计值。多变量扩展 Cox 模型和危害图用于检查接受 RT 与每种结局的风险之间的关联，调整了基线协变量和乳房 X 光检查的依从性。
人群队列包括 3262 名接受 BCS 治疗的女性；其中 1635 人接受了 RT。中位随访时间为 13 年。单独接受 BCS 治疗的 364 名妇女和接受 RT 治疗的 274 名妇女发生了 LR。LR 风险在 2 年内达到峰值，直到第 7 年下降，然后保持稳定。LR 的高峰风险与 DCIS 的不良特征有关。接受 RT 治疗的患者早期 LR 风险降低，但两组晚期 LR 和浸润性 LR 的年风险相似。多变量分析显示，RT 与早期 LR 风险降低相关（HR=0.52，95%CI 0.43-0.63，p<0.0001），但不能降低晚期 LR 风险（HR=0.89，95%CI：0.67，1.19，p=0.44）（交互作用，p=0.002）。
RT 的效果并非随时间均匀，在 BCS 后 7 年内对 DCIS 的效果最大，这可以指导未来的研究，以了解 RT 反应的机制并优化 DCIS 的未来管理。
